I would have made this a POLL but there is just too much to list.
Lets exclude Cyberstorm PPC/060 with CVision, Blizzard PPC/060 with BVision & Blizzard 2060 with PPC module as I am sure that is almost Amiga owner's top 3.
And lets exclude stuff which is still available new today, like Elbox PCI busboards, Indivision scandoubler, MiniMig etc.
If we ignore price, look at everything that was commercially available (no prototype or vapourware stuff), what is your most sought after hardware? Full computer, accelerator, sound card... right down to manuals & boxes, anything.
If it is a particular version of something (like an A4000D-CR Rev D) be specific. Please try and list the manufacturer's name if you know it. And if there is an interesting tale behind why, tell us.
Why?? When the thread is exhausted in a week or so I'll let you know.